Crawling Out of the Hole of Negativity

My personal mantra is "no mistakes, only lessons." I repeat this phrase to myself frequently as I tend to make a lot of lessons. It's easy for me to get down on myself when I make mistakes. My mind wants to endlessly review the event, which results in dark feelings enveloping me. There's no escape from the torment because I can't change what's happened in the past. Lessons, however, are a thing of the future.